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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 91 · 40 sums
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The method (Split into easy parts): (a + b)² = a² + 2ab + b². (a − b)² = a² − 2ab + b². (a + b)(a − b) = a² − b²; so a² − b² = (a + b)(a − b). a² + b² = (a + b)² − 2ab = (a − b)² + 2ab.

NameDateTime takenScore ___ / 40
  1. 1.Use a² − b² = (a + b)(a − b) to find 83² − 64².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 74².
  3. 3.Use a² − b² = (a + b)(a − b) to find 40² − 37².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 96².
  5. 5.Find the value of x² + 2xy + y² when x = 13 and y = 11.
  6. 6.Use a² − b² = (a + b)(a − b) to find 79² − 72².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 23².
  8. 8.Use (a + b)(a − b) = a² − b² to find 77 × 63.
  9. 9.Use (a + b)(a − b) = a² − b² to find 107 × 93.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 53².
  11. 11.Find the value of x² + 2xy + y² when x = 12 and y = 4.
  12. 12.Use a² − b² = (a + b)(a − b) to find 21² − 8².
  13. 13.If a − b = 9 and ab = 10, what is a² + b²?
  14. 14.Use a² − b² = (a + b)(a − b) to find 76² − 4².
  15. 15.Find the value of x² + 2xy + y² when x = 4 and y = 2.
  16. 16.Use a² − b² = (a + b)(a − b) to find 26² − 4².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 36².
  18. 18.Use a² − b² = (a + b)(a − b) to find 35² − 6².
  19. 19.Find the value of x² − 2xy + y² when x = 12 and y = 11.
  20. 20.If a + b = 3 and ab = 2, what is a² + b²?
  21. 21.Use (a − b)² = a² − 2ab + b² to find 83².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 31².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 63².
  24. 24.Find the value of x² + 2xy + y² when x = 12 and y = 2.
  25. 25.Use (a + b)² = a² + 2ab + b² to find 26².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 28².
  27. 27.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  28. 28.If a − b = 5 and ab = 6, what is a² + b²?
  29. 29.Use (a − b)² = a² − 2ab + b² to find 57².
  30. 30.If a + b = 9 and ab = 20, what is a² + b²?
  31. 31.If a + b = 21 and ab = 108, what is a² + b²?
  32. 32.Use a² − b² = (a + b)(a − b) to find 54² − 4².
  33. 33.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  34. 34.Use (a + b)(a − b) = a² − b² to find 57 × 43.
  35. 35.If a + b = 10 and ab = 24, what is a² + b²?
  36. 36.Use (a + b)(a − b) = a² − b² to find 79 × 61.
  37. 37.If a + b = 12 and ab = 20, what is a² + b²?
  38. 38.If a − b = 2 and ab = 24, what is a² + b²?
  39. 39.Use (a − b)² = a² − 2ab + b² to find 32².
  40. 40.Find the value of x² − 2xy + y² when x = 10 and y = 8.

Answer key

  1. 2793
  2. 5476
  3. 231
  4. 9216
  5. 576
  6. 1057
  7. 529
  8. 4851
  9. 9951
  10. 2809
  11. 256
  12. 377
  13. 101
  14. 5760
  15. 36
  16. 660
  17. 1296
  18. 1189
  19. 1
  20. 5
  21. 6889
  22. 961
  23. 3969
  24. 196
  25. 676
  26. 784
  27. 1599
  28. 37
  29. 3249
  30. 41
  31. 225
  32. 2900
  33. 8096
  34. 2451
  35. 52
  36. 4819
  37. 104
  38. 52
  39. 1024
  40. 4

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